The composition, sequence, length and type of glycosidic linkage of polysaccharides profoundly affect their biological and physical properties. However, investigation of the structure–function relationship of polysaccharides is hampered by difficulties in accessing well-defined polysaccharides in sufficient quantities. Here we report a chemical approach to precision polysaccharides with native glycosidic linkages via living cationic ring-opening polymerization of 1,6-anhydrosugars. We synthesized well-defined polysaccharides with tunable molecular weight, low dispersity and excellent regio- and stereo-selectivity using a boron trifluoride etherate catalyst and glycosyl fluoride initiators. Computational studies revealed that the reaction propagated through the monomer α-addition to the oxocarbenium and was controlled by the reversible deactivation of the propagating oxocarbenium to form the glycosyl fluoride dormant species. Our method afforded a facile and scalable pathway to multiple biologically relevant precision polysaccharides, including d-glucan, d-mannan and an unusual l-glucan. We demonstrated that catalytic depolymerization of precision polysaccharides efficiently regenerated monomers, suggesting their potential utility as a class of chemically recyclable materials with tailored thermal and mechanical properties.

多糖的糖苷键的组成、序列、长度和类型深刻地影响其生物学和物理性质。然而，由于难以获得足够数量的明确多糖，阻碍了对多糖结构-功能关系的研究。在这里，我们报告了一种通过 1,6-脱水糖的活性阳离子开环聚合来制备具有天然糖苷键的精密多糖的化学方法。我们使用三氟化硼乙醚催化剂和糖基氟引发剂合成了具有可调分子量、低分散性和优异区域和立体选择性的明确多糖。计算研究表明，反应通过单体α-加成到氧碳鎓上进行传播，并通过传播的氧碳鎓可逆失活形成糖基氟化物休眠物质来控制。我们的方法为多种生物学相关的精密多糖提供了一种简便且可扩展的途径，包括d-葡聚糖、d-甘露聚糖和不寻常的l-葡聚糖。我们证明了精密多糖的催化解聚可以有效地再生单体，这表明它们作为一类具有定制热性能和机械性能的化学可回收材料的潜在用途。